Answer
95 feet
Work Step by Step
Let's say that $x$ is the height of the tall tree. We can find two similar triangles by starting at the eye level of the woodcutter.
We set up a ratio between the large triangle and the small triangle:
$\frac{x-5}{25+125}=\frac{20-5}{25}$
We cross multiply to solve for $x$:
$(x-5)*25=(20-5)*(25+125)$
$25*x-125=15*150$
$25*x-125=2250$
$25*x=2375$
$x=95$
Thus the height of the tall tree is 95 feet.
